This invention relates to steered rolling devices, for example roller skates, multi tracked skates, skis on wheels.
As far as the mentioned rolling devices are to be steered by leaning sideways they steer the same way on either side. The state of the art is for example shown by US6,755,425 or EP1213043B1, which disclose a steering mechanism containing two wheels guided by a laterally oriented closed parallelogram or trapezium fourbar linkage. FIG. 1 shows the state-of-the-art steering mechanism. Part of the frame 20 is cut away so that the steering mechanism can be seen. FIG. 1 shows horizontal cross-guides 13, 14, which are rotatably secured to extensions 8 of the frame 20, the axes of rotation being 2 and 2a. In order to provide the rotation around axis 2 two spherical bushings 15, 16 are used; in order to provide rotation around axis 2a one spherical bushing 17 is used. The contour of the boot is indicated.
A pair of rolling devices is attached to the two legs of the skater. Upon slaloming, in particular when skating along a circle, both legs perform tracks with equal curvature, which are offset by the legs' distance. Hence one track crosses the other so that parallel skating is disturbed eventually causing the skater to fall down and suffer injury. This interference can be avoided by using technical means, which let the outer skate perform a wider curve than the inner skate.
DE10135481A1 discloses one solution to the problem insofar as two fixed wheels oriented one behind the other providing a lateral offset so that upon leaning to one side the first wheel has contact to the ground, upon leaning to the other side, the second wheel has contact to the ground. Hence turning left provides a wheel-base which is different from the wheel-base when turning right providing the desired difference between the left curve radius and the right curve radius. However this solution is disadvantageous, as when turning left or right either the one or the other wheel lifts from the ground which results in a bad tracking behavior. Furthermore the wheels suffer from asymmetric wear. Therefore it is desirable that the asymmetric steering is intrinsically provided by the steering mechanism itself.